1. Field of the Invention
The present invention relates to an apparatus and method for separating larger foreign bodies from granular feeds, and more specifically, relates to an apparatus for separating rocks and other waste debris from finer conveyed granular feed.
2. Description of the Prior Art
The art discloses a number of apparatus for separating stones and other debris from recently harvested potatoes. For example, U.S. Pat. Nos. 2,114,263; 2,656,921; 2,828,012; 3,198,259 and 3,211,288 all disclose various types of apparatus of the above-mentioned type. Several of the above listed patents disclose apparatus utilizing rotating cylindrical brushes mounted above a conveyor carrying the potatoes, stones, and other debris. The axis of the cylindrical brush is at an angle with respect to the direction of travel of the conveyor.
German Pat. No. 512,397 discloses a rotating shaft having a number of radially extending paddles attached thereto. The shaft with the paddles is positioned over a trough carrying mined coal. The paddles are of varying length in order to separate the chunks of mined coal into various size ranges.
There has been a need in the art of conveying granular materials, especially granular materials having a size in the range of less than about 3 Tyler mesh, for a device capable of economically separating and removing oversized foreign objects from the granular feeds.
In past years, petroleum coke which had become contaminated with dirt and other foreign materials, could not be sufficiently cleaned for its intended uses as a fuel. Thus in past years, contaminated coke was disposed of, typically by burial. Recently, new methods of purifying contaminated coke have been developed. Furthermore, the economic value of petroleum coke has risen dramatically over the years. In addition, stricter environmental laws now discourage the disposal of petroleum coke products by burial. As a result of these influences, contaminated petroleum coke which until recently had been discarded and buried, is now being reclaimed for use as fuels. Of course, in reclaiming buried petroleum coke, significant amounts of rock and other foreign materials are also gathered. Thus, there has been a need in the art of reclaiming contaminated petroleum coke for an economical method of separating larger foreign bodies from granulated petroleum coke having a size in the range of less than about 3 Tyler mesh.
While the prior art discloses various screening steps for removing larger foreign bodies from a granular material, these screening steps are extremely expensive from a material processing cost standpoint. Thus, it is a further object of the present invention to provide a more economical means for removing larger foreign bodies from a finer granular feed.